Mix mail feeder

1. A feeder for feeding envelopes in a mail handling machine comprising a transport deck for receiving a stack of envelopes, feed rollers for conveying downstream envelopes towards a reference wall leaving a clearance path for the envelopes, a stack sensor for detecting the presence of said stack of envelopes at a predetermined height threshold, and a control unit for activating the feed rollers, wherein the control unit is configured for applying a determined acceleration to said feed rollers and for decreasing said determined acceleration of said feed rollers when the stack of envelopes goes below said predetermined height threshold in order to separate remaining envelopes of the stack.

2. The feeder of claim 1 , wherein said acceleration is decreased from a first acceleration to a second acceleration.

3. The feeder of claim 2 , wherein said first acceleration is a higher acceleration of 100 m/s2 and said second acceleration is a lower acceleration of 20 m/s2.

4. The feeder of claim 1 , wherein said control unit is further configured for maintaining a top speed of said feed rollers when the stack of envelopes goes below said predetermined height threshold.

5. The feeder of claim 1 , wherein said control unit is further configured for limiting a top speed of said feed rollers when the stack of envelopes goes below said predetermined height threshold.

6. The feeder of claim 1 , wherein said reference wall extends vertically from said transport deck.

7. The feeder of claim 6 , wherein said stack sensor is placed in said reference wall just above said clearance path.

8. The feeder of claim 1 , wherein said stack sensor is a contact sensor protected by an articulated lever or an optical reflective sensor.

9. The feeder of claim 1 , wherein it further comprises a feed sensor located below said transport deck and near said reference wall.

10. The feeder of claim 9 , wherein said control unit is further configured for, in an initialization phase, if said envelopes are detected by said feed sensor, activating said feed rollers to advance the entire stack of envelopes towards the reference wall.

11. The feeder of claim 1 , wherein it further comprises friction pads facing separation rollers for ejecting one by one said envelopes from said stack.

12. A mail handling machine, comprising:

feeder for feeding envelopes, the feeder comprising:

a transport deck sized, dimensioned and positioned to receive a stack of envelopes;

a number of feed rollers positioned and operable to convey envelopes downstream towards a reference wall leaving a clearance path for the envelopes;

a stack sensor positioned to detect a presence of said stack of envelopes at a predetermined height threshold; and

a control unit communicatively coupled to selectively activate the feed rollers, wherein the control unit determines an acceleration to be applied to said feed rollers and decreases said determined acceleration of said feed rollers in response to the stack of envelopes being below said predetermined height threshold in order to separate remaining envelopes of the stack.

13. The mail handling machine of claim 12 , wherein the controller decreases said acceleration from a first acceleration to a second acceleration in response to the stack of envelopes being below said predetermined height threshold.

14. The mail handling machine of claim 13 , wherein said first acceleration is a higher acceleration of about 100 m/s2 and said second acceleration is a lower acceleration of about 20 m/s2.

15. The mail handling machine of claim 12 , wherein when the stack of envelopes is below said predetermined height threshold, said control unit maintains a top speed of said feed rollers.

16. The mail handling machine of claim 12 , wherein when the stack of envelopes goes below said predetermined height threshold, said control unit limits a top speed of said feed rollers.

17. The mail handling machine of claim 12 , wherein said reference wall extends vertically from said transport deck and said stack sensor is placed in said reference wall just above said clearance path.

18. The mail handling machine of claim 12 , wherein said stack sensor is a contact sensor protected by an articulated lever or an optical reflective sensor.

19. The mail handling machine of claim 12 , wherein the feeder further comprises a feed sensor located below said transport deck and near said reference wall, and wherein, in an initialization phase, if said envelopes are detected by said feed sensor, said control unit activates said feed rollers to advance the entire stack of envelopes towards the reference wall.

20. The mail handling machine of claim 12 , wherein the feeder further comprises a number of friction pads facing separation rollers that eject said envelopes from said stack, one by one.